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Find the unknown sizes of angles in the following figure

Find the unknown sizes of angles in the following figure-example-1

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Answer:

see explanation

Explanation:

The sum of the interior angles of a quadrilateral = 360°

sum the 4 angles and equate to 360

y + 3y + y + 30 + 90 = 360 , that is

5y + 120 = 360 ( subtract 120 from both sides )

5y = 240 ( divide both sides by 5 )

y = 48

3y = 3 × 48 = 144

y + 30 = 48 + 30 = 78

The measure of the 4 angles are

48°, 78° , 90° , 144°

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